.......... ahhhh, country PO's. Had the same experience re Large letter. Simply ask them to show you from the postal charges book where this stated. We have 'educated' many PO s over the years! Our local now asks us if it is a large letter LOL!
You can sneak a large letter thru if it is just over thickness - or weight (maybe 10 / 20g) and post it outside in the collection box. This I do after being charged Parcel ($6.95) because it was 502g. (A sheet of paper weighs 5g). So, if the book is over 20mm thick, it is going to cost at least $6.95 up to 500g, after that it becomes interesting .... $11.45 plus up to $5+ (depending on where you are and where it is going) for up to 1kg.
Have fun!
